Graceful Queues: Issue Indexing and Tasks (#9363)

* Queue: Add generic graceful queues with settings

* Queue & Setting: Add worker pool implementation

* Queue: Add worker settings

* Queue: Make resizing worker pools

* Queue: Add name variable to queues

* Queue: Add monitoring

* Queue: Improve logging

* Issues: Gracefulise the issues indexer

Remove the old now unused specific queues

* Task: Move to generic queue and gracefulise

* Issues: Standardise the issues indexer queue settings

* Fix test

* Queue: Allow Redis to connect to unix

* Prevent deadlock during early shutdown of issue indexer

* Add MaxWorker settings to queues

* Merge branch 'master' into graceful-queues

* Update modules/indexer/issues/indexer.go

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

* Update modules/indexer/issues/indexer.go

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

* Update modules/queue/queue_channel.go

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

* Update modules/queue/queue_disk.go

* Update modules/queue/queue_disk_channel.go

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

* Rename queue.Description to queue.ManagedQueue as per @guillep2k

* Cancel pool workers when removed

* Remove dependency on queue from setting

* Update modules/queue/queue_redis.go

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

* As per @guillep2k add mutex locks on shutdown/terminate

* move unlocking out of setInternal

* Add warning if number of workers < 0

* Small changes as per @guillep2k

* No redis host specified not found

* Clean up documentation for queues

* Update docs/content/doc/advanced/config-cheat-sheet.en-us.md

* Update modules/indexer/issues/indexer_test.go

* Ensure that persistable channel queue is added to manager

* Rename QUEUE_NAME REDIS_QUEUE_NAME

* Revert "Rename QUEUE_NAME REDIS_QUEUE_NAME"

This reverts commit 1f83b4fc9b.

Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>
Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: techknowlogick <matti@mdranta.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

modules/queue/queue_channel.go

@@ -0,0 +1,106 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package queue
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+	"time"
+
+	"code.gitea.io/gitea/modules/log"
+)
+
+// ChannelQueueType is the type for channel queue
+const ChannelQueueType Type = "channel"
+
+// ChannelQueueConfiguration is the configuration for a ChannelQueue
+type ChannelQueueConfiguration struct {
+	QueueLength  int
+	BatchLength  int
+	Workers      int
+	MaxWorkers   int
+	BlockTimeout time.Duration
+	BoostTimeout time.Duration
+	BoostWorkers int
+	Name         string
+}
+
+// ChannelQueue implements
+type ChannelQueue struct {
+	pool     *WorkerPool
+	exemplar interface{}
+	workers  int
+	name     string
+}
+
+// NewChannelQueue create a memory channel queue
+func NewChannelQueue(handle HandlerFunc, cfg, exemplar interface{}) (Queue, error) {
+	configInterface, err := toConfig(ChannelQueueConfiguration{}, cfg)
+	if err != nil {
+		return nil, err
+	}
+	config := configInterface.(ChannelQueueConfiguration)
+	if config.BatchLength == 0 {
+		config.BatchLength = 1
+	}
+	dataChan := make(chan Data, config.QueueLength)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	queue := &ChannelQueue{
+		pool: &WorkerPool{
+			baseCtx:            ctx,
+			cancel:             cancel,
+			batchLength:        config.BatchLength,
+			handle:             handle,
+			dataChan:           dataChan,
+			blockTimeout:       config.BlockTimeout,
+			boostTimeout:       config.BoostTimeout,
+			boostWorkers:       config.BoostWorkers,
+			maxNumberOfWorkers: config.MaxWorkers,
+		},
+		exemplar: exemplar,
+		workers:  config.Workers,
+		name:     config.Name,
+	}
+	queue.pool.qid = GetManager().Add(queue, ChannelQueueType, config, exemplar, queue.pool)
+	return queue, nil
+}
+
+// Run starts to run the queue
+func (c *ChannelQueue) Run(atShutdown, atTerminate func(context.Context, func())) {
+	atShutdown(context.Background(), func() {
+		log.Warn("ChannelQueue: %s is not shutdownable!", c.name)
+	})
+	atTerminate(context.Background(), func() {
+		log.Warn("ChannelQueue: %s is not terminatable!", c.name)
+	})
+	go func() {
+		_ = c.pool.AddWorkers(c.workers, 0)
+	}()
+}
+
+// Push will push data into the queue
+func (c *ChannelQueue) Push(data Data) error {
+	if c.exemplar != nil {
+		// Assert data is of same type as r.exemplar
+		t := reflect.TypeOf(data)
+		exemplarType := reflect.TypeOf(c.exemplar)
+		if !t.AssignableTo(exemplarType) || data == nil {
+			return fmt.Errorf("Unable to assign data: %v to same type as exemplar: %v in queue: %s", data, c.exemplar, c.name)
+		}
+	}
+	c.pool.Push(data)
+	return nil
+}
+
+// Name returns the name of this queue
+func (c *ChannelQueue) Name() string {
+	return c.name
+}
+
+func init() {
+	queuesMap[ChannelQueueType] = NewChannelQueue
+}